The subject matter of the present disclosure broadly relates to the art of sheet compiling systems and, more particularly, to a variable-speed compiling system, such as may be used as a post-processing collator or in association with a finishing unit of a printing system, for example, as well as a method of compiling sheet media using the same.
Sheet handling systems of many types and kinds are known to utilize sheet compiling systems to collect and organize sheets of media into one or more packets or stacks thereof. For example, printing systems are known to use finishing units of a variety of types and kinds to receive sheets of media output by a marking engine or other section of the printing system. Typically, such known finishing units operate to organize the sheets of media into one or more packets or groups of sheets, such as into collated or uncollated stacks, for example. In many cases, known finishing units are also adapted to perform one or more further operations on these one or more groups of sheets, such as stapling or hole punching operations, for example.
Typically, it is desirable for known finishing units to at least approximately align one or more edges of the sheets of media in each group so that any further operations will produce uniform output. For example, it is often desirable to approximately align two adjacent edges of the sheets of media prior to a stapling operation such so that the resulting stapled packets of media will have a uniform appearance. As another example, it is normally desirable to approximately align two adjacent edges of the sheet of media prior to a hole punching operation so that all of the sheets of media will be hole punched in approximately the same locations, which will permit the sheets of media to be inserted, such as in an associated binder, in a uniform manner.
Known finishing units and other sheet handling systems commonly include a compiler or compiling system to assist in approximately aligning the sheets of media with one another. Typically, such compilers will include at least one collection tray for receiving the sheets of media. The collection tray normally includes a bottom wall for supporting the sheets of media and at least one registration wall that projects in an approximately transverse direction from the bottom wall. The at least one registration wall can then be used for approximately aligning edges of the sheets of media.
One example of such an arrangement, which is often referred to in the art as an “uphill” compiler, includes a collection tray that has bottom wall with a proximal end and a distal end. Typically, the distal end extends above the proximal end so that the bottom wall is disposed in an “uphill” orientation with respect to the sheet media being received at the finishing unit. The registration wall of the collection tray projects from the bottom wall along the proximal end thereof. Sheets of media enter the collection tray from along the proximal end such that the leading edge of the sheets of media is disposed toward the distal end of the collection tray and the trailing edge is disposed toward the proximal end of the collection tray. During use, the sheets of media are delivered into the collection tray with sufficient speed for the sheets of media to settle onto the bottom wall with the trailing edge of the sheets being spaced a short distance from the registration wall. The sheets of media then slide back toward the proximal end under the influence of gravity until the trailing edge of the sheets of media is at least approximately aligned with the registration wall.
Due to certain operational characteristics of uphill compilers, the same tend to be better suited for use in association with systems having lower output rates, such as less than 100 pages per minute (ppm), for example. This may be due, at least in part, to the time required for gravity to accelerate each sheet downhill and into approximate alignment with a registration wall. As such, the use of such uphill compilers is often avoided in sheet handling and/or printing systems that operate at higher output rates.
Other compilers or compiling systems have been developed to provide improved performance, such as the ability to handle higher printing system output rates, for example. Such compiling systems are often referred to in the art as “friction” compiling systems due to the use of an element that frictionally engages each sheet of media to urge the same toward the one or more registration walls. However, certain undesirable characteristics are often associated with known friction compiling systems.
For example, friction compilers typically include a frictional element that engages each individual sheet of media as the same is being received at or along the collection tray. The frictional element drives each sheet of media toward at least one registration wall such that at least the leading edge of successive sheets of media will be aligned with one another. One difficulty with such arrangements, however, is that causing the leading edge of the sheets of media to impact the registration wall with too much force can occasionally result in the sheet being undesirably deformed (e.g., wrinkled or folded). In other cases, such levels of impact force may result in the sheets of media bouncing back or otherwise away from the one or more registration walls. Oppositely, imparting insufficient drive force on the sheets of media can result in some of the sheets of media failing to reach the registration wall.
Accordingly, it is believed desirable to develop a compiling system for a finishing unit of a printing system and method of operating the same that overcomes the foregoing and/or other issues.